Learn how to work with spot and process colors, understand how each printing method reproduces color, and choose the right color type for your final output.
Spot and process colors are the two primary ink methods used in commercial printing. In most design applications, you can identify the color type using the icons or labels displayed next to the color name.
Spot colors
A spot color is a special premixed ink that replaces or supplements process inks. As spot colors require their own printing plates, you use them when a few colors are needed, and precise color accuracy is critical. Spot color inks can accurately reproduce colors outside the process printing gamut.
The combination of ink mixed by the commercial printer and the paper determines the exact appearance of a printed spot color, not the color values or color management. Any spot color values you specify simulate the appearance of the color on your monitor or composite printer only (subject to the gamut limitations of those devices).
Follow the guidelines when using spot colors:
- Choose colors from a supported color-matching system: For printing, select spot colors from a standardized color library supported by your commercial printer.
- Limit the use of spot colors to reduce costs: Each spot color requires an additional printing plate, which increases your printing costs. If your project requires more than four colors, consider using process colors instead.
- Preview and manage spot color interactions with transparency: When an object with spot colors overlaps a transparent object, this interaction can produce unexpected results during EPS export, spot-to-process conversion in the Print dialog box, or when you create separations in applications other than Illustrator or InDesign. To ensure accurate output, use Flattener Preview or Separations Preview before printing. For greater reliability, convert spot colors to process colors in advance using the Ink Manager in InDesign before printing or exporting.
- Use spot-color printing plates for varnish: You can use a spot-color printing plate to apply varnish or coating to selected areas of a printed piece. In this case, the printing uses four process inks and a spot varnish ink.
Process colors
A process color is produced by combining the four standard process inks: cyan, magenta, yellow, and black (CMYK). Use process colors when a project includes many colors, such as photographs or complex illustrations, where using individual spot inks would be expensive or impractical.
Follow the guidelines when specifying a process color:
- Use CMYK values from a reliable reference.
For best results in a high-quality printed document, specify process colors using CMYK values printed in process color reference charts, such as those available from a commercial printer. - Understand how color conversions occur.
The final appearance of a process color is determined by its CMYK values. If you define a color in another mode, such as RGB or Lab, it will be converted to CMYK during color separation. The results of these conversions depend on your document profile and color-management settings. - Don’t rely solely on your monitor for accuracy.
Avoid choosing process colors based solely on how they appear on screen unless you have set up a color-management system properly, and you understand its limitations. - Avoid defining colors in CMYK for online-only content.
Process colors have a smaller gamut than most displays, so CMYK values are not recommended for artwork intended exclusively for digital or web use. - Understand how global and non-global process colors behave.
Some design tools allow process colors to be defined as global or non-global. Global colors remain linked to a swatch, so any updates to the swatch automatically update all objects using that color. Non-global colors are not linked, and editing one instance does not affect others.
Global and non-global colors affect how a color is applied to objects. They don't change color separations or how the colors behave when transferred between apps.
Use spot and process colors together
Using process and spot inks together can be practical. For example, you may use a spot ink to reproduce a brand color with exact color using process inks to print photographs in an annual report. A spot-color plate can also be used to apply varnish to selected areas. In these cases, the print job uses five inks, four process inks plus one spot ink or varnish.
You can compare colors in InDesign and Illustrator to learn how color modes behave across apps.
